Abstract: The roof of large span roadway in thick coal was soft and broken and the separation of expansion was easily happened in this roof. These features can easily led to the broken of anchor ropes and the destruction of support structure, and caused the roof fall accident. The large area roof fall of 20322 haulageway during roadway excavation was chosen as the research background. The paper analysised the pressure phenomenon before the roadway roof-fall accident and concluded that the main reasons for the instability of the roof structure were the fractured surrounding rock and the unreasonable parameters of anchor cables. The supporting idea of enhance the integrity and strength of the roof support structure through the adjustment of the anchor cable supporting parameters to control the soft thick coal roof was proposed and good results have been achieved in the practice of the industry.